Process for reducing the 2,4-dialkylphenol content in the manufacture of monoalkylphenol



United States Patent 3,417,151 PROCESS FOR REDUCING THE 2,4-DIALKYL- PHENOL CONTENT IN THE MANUFACTURE OF MONOALKYLPHENOL Edward F. Riener, Cinnaminson, N.J., and Thomas J. Durkin, Philadelphia, Pa., assignors to Rohm & Haas Company, Philadelphia, Pa., a corporation of Delaware No Drawing. Continuation-impart of application Ser. No. 142,789, Oct. 4, 1961. This application Sept. 29, 1964, Ser. No. 400,215

5 Claims. (Cl. 260624) ABSTRACT OF THE DISCLOSURE Process for separating monoalkylphenol and 2,4-dialkylphenol from a mixture of the two which results from the alkylation of phenols. The separation is accomplished by adding boric acid to form a borate ester with the 2,4-dialkylphenol, then distilling off the monoalkylphenol along with some non-esterified products.

This is a continuation-in-part of our application Ser. No. 142,789 which was filed on October 4, 1961, now abandoned.

This invention relates to a process for the manufacture of 'alkylphenols, particularly monoalkylphenol, by the alkylation of phenols with olefins. It has particular reference to a method whereby monoalkylphenol and 2,4-dialkylphenol are the primary products, and to an improvement thereto whereby the proportion of monoalkylphenol which is produced is increased in comparison with the 2,4-dialkylphenol content in the end product.

The art has long known of numerous procedures for manufacturing alkylphenols from phenols and olefins, and in making such products as octyl or nonylphenols and the like has invariably found the higher boiling 2,4- dialkylphenol in the yield along with the lower boiling monoalkylphenol. In many applications the presence of a sizable quantity of the 2,4-dialkylphenol is objectionable, and it must be reduced to acceptable limits or else the product may not be very useful. One obvious Way to reduce the 2,4-dialkylphenol content is to fractionally.

distill the material, but this requires elaborate equipment which in many plants may be prohibitive for economic reasons. Thus, a simple, relatively inexpensive way of reducing the amount of 2,4-dialkylphenol present has long been needed, and to obtain a solution to this long felt need is the principal object of the present invention.

We have found that a very satisfactory solution to the problem is to add boric acid to the crude alkylphnol product which is obtained upon alkylation of the phenol in the normal manner. The quantity of boric acid is comparatively very small, as only enough is needed to tie up a .sufiicient amount of the 2,4-dialkylphenol to bring the level thereof down to acceptable tolerances. Once so tied up, simple distillation will remove the monoalkylphenol and any residual phenol. The 2,4-dialkylphenol, having formed a borate ester, remains as a residue because of its high boiling nature. If desired, this residue may be hydrolized to produce a product rich in the amount of 2,4-dialkylphenol it contains.

The amount of boric acid needed will depend on the amount of 2,4-dialkylphenol present and the degree to which it is desired to lower the amount of 2,4-dialkylphenol in the end product. The more boric acid that is added, the more of the 2,4-dialkylphenol present hecomes tied up. Eventually, this ability to tie up the 2,4-dialkylphen0l falls off, as 100% of the dialkylphenol cannot be removed, but one can get rather close to that goal in the normal alkylphenol manufacturing processes ice and still not need to add enough boric acid to cause any objectionable side effects. Generally speaking, the amount of boric acid which is preferred is about 0.5 to 3.0 times the amount necessary to react quantitatively with the 2,4-dialkylphenol present.

The effectiveness of this invention can be appreciated from the following examples.

Example 1 Original Product After Boric Product Acid Treatment Phenol 0. 4 0.3 p-t-Butylphenol 0. 2 0. Tetra-iso-butyle o-Octylphenol 1. 4 1. 5

p-O ctylphenol. 89. 3 94. 0

Unknown 1.1 1.2 1. 1 2,4-dioctylpheno1 7. 5 2. 9

Example 2 A synthetic mixture of octylphenol and 2,4-dioctylphenol was prepared and heated with boric acid to demonstrate the method of this procedure. Nine (9) grams of boric acid were added to 383 grams of the synthetic mixture and the material was distilled by the standard procedure. The bulk of the product came over at 174" C./l5 mm. The original and the distilled materials had the following gas chromatographic analyses:

Original Product After Boric Product Acid Treatment Phenol 0.7 p-tr-Butylphenol 0. 8 0. 7 o-OctylphenoL- 1. 4 2. 1 p-Octylphenol. 82. 1 91. 9 Unknown 1.1.. Trace Nil 2,4-dioctylphenol 14. 9 5. 3

Example 3 A sample of 400 grams of plant nonylphenol, which upon analysis proved to have 22.4% 2,4-dinonylphenol, was distilled by the standard process at a pressure of 10 mm. and the product was collected when the vapor pressure initially reached 167 C. (pot temperature 175 C.). The pot temperature was gradually raised to Fraction Weight, Grams Boiling Range/10 mm. 4 Up to 55 0. 6 55-160" C. 346 1G0l85 C. 30 1s5-215 C.

6 Residue.

Five grams of boric acid were added to 400 grams of another sample of the same nonylphenol, and the material was distilled in a like manner. The results were as follows:

Fraction Weight, Grams Boiling Range/10 mm.

3 Up to 55 0 5 55-150 0 315 160167 0 2O 73 Residue Whereas Fraction III of the untreated plant crude nonylphenol had 22.4% 2,4-dialkylphenol, upon analysis, Fraction III of the boric acid treated material had 3% of 2,4-dinonylphenol.

32,695 lbs. Product; 0 U m X 1d The crude nonylphenol used was analyzed and found to contain 20% 2,4-dialky1phenol. The products, upon analysis, were found to have the following percentages of dialkylphenol:

Percent Lot 2,4-dialkylphenol 1 8.9

The decrease in 2,4-dialkylphenol content averaged about We claim:

1 The process of separating a monoalkylphenol and 2,4-dialkylphenol from a mixture of the two which comprises adding to the mixture at least about 0.5 times the amount of boric acid necessary to form the borate ester with 2,4-dialkylphenol, and then distilling off the monoalkylphenol along with some non-esterified products.

2. The method of claim 1 in which the crude monoalkylphenol is mainly octylphenol.

3. The method of claim 1 in which the crude monoalkylphenol is mainly nonylphenol.

4. The method of claim 1 in which the quantity of boric acid which is added is from 0.5 to 3.0 times the amount necessary to react quantitatively with the 2,4- dialkylphenol present.

5. The method of claim 1 in which the non-distillable residue is hydrolyzed to provide a product containing most of the 2,4-dia1kylpheno1 and a reduced amount of the monoalkylphenol which were present in the original mixture.

References Cited UNITED STATES PATENTS 2,236,811 4/1941 Dryer 260624 2,248,830 7/ 1941 Stillson et a1. 260624 2,353,282 7/1944 Turkington et al. 260624 2,260,338 10/ 1941. Prescott et a1. 260624 2,899,470 8/1959 Goldstein et al. 260624 LEO'N ZITVER, Primary Examiner. W. B. LONE, Assistant Examiner. 

